The cross has become one of the most enduring and well-recognized Christian symbols throughout the world. You'd almost never guess that it started out as a way to kill people.
Imagine seeing a little girl with a pretty electric chair charm around her neck or watching your great aunt hang a decorative noose on her front door. That should give you an idea of how much the symbol of the cross has changed over the years. What was once an exceptionally cruel method of capital punishment has become a sign of hope and inspiration for billions.
The early Christians didn't focus much on the cross right after Jesus died—probably because they actually knew what death on a cross would have looked like. It wasn't a pretty sight.
Crucifixion was a particularity terrible and humiliating punishment used throughout the Roman Empire. A victim would be stripped naked, have nails pounded through their arms or feet (or both), be placed upright on the cross, and be left to die. Since the nails alone wouldn't kill you, the death was slow. Victims often died from starvation, suffocation, or shock, and depending on the method that was used, death could take hours or days. Not exactly something you want to imagine your Savior going through.
Within the New Testament, the authors attempt to reclaim the symbol of the cross. Rather than being a humiliating method of execution, the cross comes to represent God's wonderful plan of salvation.
The Gospel of John is definitely on board. At every step, Jesus's death is described as the glorious fulfillment of all God wants for the world. Even the agony of crucifixion doesn't seem so bad in this particular version of the story. While hanging on the cross, Jesus says that he is thirsty not because he actually is, but to fulfill a prophecy from the Hebrew Bible (19:28).
Starting with people like the writers of the Gospel of John, this new understanding of the cross caught on and crosses became a more popular and widely known symbol of Christian devotion. For centuries, the death of Jesus has been a favorite subject for artists and authors around the world.
How about a few examples?
Because of its simplicity, the cross is often spotted in unlikely places. During the search for survivors at the site of the fallen World Trade Center, two huge steel beams in the shape of a cross were found. Many people interpreted this as a symbol of hope and solace. Two millennia later, and the cross is still going strong.